New Link Discovered Between Gut Bacteria and Obesity

Researchers have discovered a new link between our gut bacteria and obesity. The team of researchers at Lund University in Sweden found that certain amino acids in our blood can be connected to both obesity and the composition of our gut microbiota.

An increasing number of research studies indicate that the gut microbiota plays an important role in our health.
While many studies on animals have found a direct causal link between obesity, type 2 diabetes and cardiovascular disease – and our gut bacteria, there still a huge amount to discover in how the make up of our gut bacteria affects us as humans.
Previous studies have found that people suffering from these diseases have varying occurrence of different metabolites, – small molecules or metabolic residues in the bloodstream.

The aim of the current study was to identify metabolites in the blood that can be linked to obesity (high body mass index, or BMI) and to investigate whether these obesity-related metabolites affect the composition of the bacterial flora in stool samples.

Lund University’s Professor Marju Orho-Melander and co-authors analyzed blood plasma and stool samples from 674 participants in the Malmö Offspring Study, MOS. They found 19 different metabolites that could be linked to the person’s BMI; glutamate and so-called BCAA (branched-chain and aromatic amino acids) had the strongest connection to obesity.

They also found that the obesity-related metabolites were linked to four different intestinal bacteria (Blautia, Dorea and Ruminococcus in the Lachnospiraceae family, and SHA98).
“The differences in BMI were largely explained by the differences in the levels of glutamate and BCAA,” Professor Orho-Melander said.
“This indicates that the metabolites and gut bacteria interact, rather than being independent of each other.”

By far the strongest risk factor for obesity in the study, glutamate, has been associated with obesity in previous studies, and BCAA has been used to predict the future onset of type 2 diabetes and cardiovascular disease.

“This means that future studies should focus more on how the composition of gut bacteria can be modified to reduce the risk of obesity and associated metabolic diseases and cardiovascular disease,” Professor Orho-Melander said.

“To get there, we first need to understand what a healthy normal gut flora looks like, and what factors impact the bacterial composition. This requires large population studies as well as intervention studies.”